Highest temperature in London on July 20?

Platform comparison

Market context

The real-world event is the highest temperature recorded at London City Airport on 20 July 2026, measured in degrees Celsius and resolved via Wunderground history. With the settlement window closing at 12:00 UTC on 2026-07-20 and the crowd-implied probability for any “YES” outcome at 0%, the market is effectively priced as closed or already resolved, reflecting that the date has passed and the result is known.

Historically, mid-July highs in London typically range between 18°C and 28°C, with extreme outliers reaching 32°C–35°C during heatwaves; however, because 20 July 2026 is in the past relative to today (21 July 2026), comparable cases are irrelevant for forecasting and instead serve only to contextualise why a 0% probability is logical once the event has occurred. Programmatic traders would bypass this market entirely, as conditional orders or copy-trading bots cannot act on a resolved event, and any API polling of Wunderground for EGLC on that date would return a fixed historical value rather than a probabilistic signal.

No catalysts remain to watch, as there are no pending announcements, schedules, or dependencies for a past date; the resolution source is static historical data, not forward-looking forecasts. A trader evaluating tooling would note that markets with settlement dates in the past fail standard backtesting frameworks for live strategy deployment, and any attempt to automate entry would trigger immediate rejection by exchange logic. Recent weather summaries from BBC Weather confirm current London conditions are 13°C, but this has no bearing on the resolved July 20 value, which is already embedded in the 0% pricing.

Sources: 1 · 2

Methodology

We track Highest temperature in London on July 20? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Polymarket Review UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Polymarket Review UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.